This invention concerns radio frequency identification devices designed to be affixed on objects such as security documents and specifically concerns a radio frequency identification device resistant to humid environments and its manufacturing method.
Contactless Radiofrequency Identification Devices (RFIDs) are increasingly used for identification of persons moving about in controlled access zones or transiting from one zone to another. A contactless RFID is a device made up of an antenna and a chip connected to the terminals of the antenna. The chip is usually not powered and receives its energy by an electromagnetic coupling between the antenna of the reader and the antenna of the RFID, information is exchanged between the RFID and the reader and particularly information stored in the chip that relates to the identification of the holder of the object on which the RFID is located and to his/her authorization to enter into a controlled access zone.
In this manner, passports can incorporate RFIDs to identify the passport holder. The chip memory contains information such as the identity of the passport holder, his/her country of origin, his/her nationality, visas of different countries visited, dates of entry, restrictions of movements, biometric elements, etc. The RFID device is generally incorporated into the bottom cover board of the passport. An antenna is then screen-printed using ink loaded with particles of silver on the reinforced bottom cover board of the passport cover. The chip is then connected by gluing to the connection terminals of the antenna. Then, the flyleaf of the quire of passport pages is laminated to the back of the reinforced top cover board. This embodiment has a drawback, as it is not waterproof and particularly cannot resist the passage of the passport through a washing machine. If the paper on which the antenna is screen-printed is not water resistant, the latter absorbs water and swells up, which causes fractures of the antenna and therefore a rupture of the electrical connection between the antenna and the chip.
This problem can be overcome by the use of an RFID device made up of a plastic “inlay”. In this case, the inlay includes the antenna and the chip, the whole assembly being embedded in plastic layers. The inlay is then bonded between the flyleaf and the passport cover. One of the drawbacks of such an RFID device is the difference in material between the inlay and the passport. The latter being made of plastic, the bonding between the two is not optimal. Furthermore, a plastic inlay does not have the advantage of paper that can be delaminated over its thickness in case of an attempt to pull out and thereby destroy the RFID circuit.